The invention relates to provision of an economical shuttle-type flow sensor capable of monitoring threshold flows of gases at high-volume flow rates.
Flow sensors presently used to monitor gas flows are either expensive because of their complexity or inaccurate and failure-prone, because of their inability to perform controllably in the unstable environment associated with the compressibility of gases.
On the other hand, in the relatively incompressible environment of liquids, flow switches such as the FS-200 and FS-400 series devices of Gems Sensors Division of Imo Industries, Inc., Plainville, Conn. provide monitored liquid flow with accurate repeatability. The construction of such devices may utilize a valve body, with provision for accommodating the displacement of a magnet-equipped shuttle, as flow increases to a predetermined set point at which a hermetically sealed reed switch is actuated to produce an output signal, as by having the actuated reed switch operate a remote alarm or indicator, or by integrating the reed switch into an automatic system control. But the liquid-flow capability of such a flow switch has been a limiting factor, rendering the same incapable of serving flow-switch purposes in a gas-flow environment.